This disclosure relates in general to correcting shading effects in an image sensor. More specifically, but not by way of limitation, this disclosure relates to dynamically correcting digitally converted outputs from pixels in the image sensor for shading effects at a Bayer domain using correction functions of elliptical-type or circular-type equations and pixel position on a pixel array in the image sensor to ascertain a correction factor for shading effects before the output from the image sensor is interpolated and/or converted to a standard video format.
In an image sensor light entering the image sensor through a lens is never truly collimated. As a consequence image sensors, including CMOS image sensors, suffer from a phenomenon known as “shading.” Shading originates from the fact that light detected by photo-sensitive elements in the image sensor that are remote from the center of the image sensor array is obliquely incident upon the remote photo-sensitive elements, whereas the light detected by photo-sensitive elements at the center of the image sensor array is substantially perpendicularly incident upon the central photo-sensitive elements. As a consequence, the light incident on the remote photo-sensitive elements may not completely fall on the remote photosensitive elements and/or may be shaded from the remote photosensitive elements by structures in the image sensor. As such, to obtain a true or at least a more accurate representation of an object from the image sensor it is necessary to compensate the outputs of the photo-sensitive elements in different locations on the image sensor array for the variable shading effect. However, shading corrections made after color interpolation, demosaicing and/or video standardization may be complicated because raw output data from pixels may be lost and more image data may now be associated with the differently shaded pixels on the image sensor. Further, shading approximation measurements found from testing of the image sensor are often not practicable to apply to pixel outputs because of the large memory necessary to store such data and the associated power requirements necessary for operating such a large memory. It is, therefore, desirable to have a shading correction method and/or system that can accurately correct shading for pixels that does/do not require large amounts of memory
In the appended figures, similar components and/or features may have the same reference label.